Created on:   	25/01/2017 09:35
 Created by:   	Jim Moyle
 Github: https://github.com/JimMoyle/YetAnotherWriteLog
 Twitter: @jimmoyle

    .SYNOPSIS

    Single function to enable logging to file.
    .DESCRIPTION

    The Log file can be output to any directory. A single log entry looks like this:
    2018-01-30 14:40:35 INFO:    'My log text'

    Log entries can be Info, Warning, Error or Debug

    The function takes pipeline input and you can pipe exceptions straight to the function for automatic logging.

    The $PSDefaultParameterValues built-in Variable can be used to conveniently set the path and/or JSONformat switch at the top of the script:

    $PSDefaultParameterValues = @{"Write-Log:Path" = 'C:\YourPathHere.log'}

    $PSDefaultParameterValues = @{"Write-Log:JSONformat" = $true}

    .PARAMETER Message

    This is the body of the log line and should contain the information you wish to log.
    .PARAMETER Level

    One of four logging levels: INFO, WARNING, ERROR or DEBUG.  This is an optional parameter and defaults to INFO
    .PARAMETER Path

    The path where you want the log file to be created.  This is an optional parameter and defaults to "$env:temp\PowershellScript.log"
    .PARAMETER StartNew

    This will blank any current log in the path, it should be used at the start of your code if you don't want to append to an existing log.
    .PARAMETER Exception

    Used to pass a powershell exception to the logging function for automatic logging, this will log the excption message as an error.
    .PARAMETER JSONFormat

    Used to change the logging format from human readable to machine readable format, this will be a single line like the example format below:
    In this format the timestamp will include a much more granular time which will also include timezone information.  The format is optimised for Splunk input, but should work for any other platform.

    {"TimeStamp":"2018-02-01T12:01:24.8908638+00:00","Level":"Warning","Message":"My message"}

    .EXAMPLE
    Write-Log -StartNew
    Starts a new logfile in the default location

    .EXAMPLE
    Write-Log -StartNew -Path c:\logs\new.log
    Starts a new logfile in the specified location

    .EXAMPLE
    Write-Log 'This is some information'
    Appends a new information line to the log.

    .EXAMPLE
    Write-Log -level Warning 'This is a warning'
    Appends a new warning line to the log.

    .EXAMPLE
    Write-Log -level Error 'This is an Error'
    Appends a new Error line to the log.

    .EXAMPLE
    Write-Log -Exception $error[0]
    Appends a new Error line to the log with the message being the contents of the exception message.

    .EXAMPLE
    $error[0] | Write-Log
    Appends a new Error line to the log with the message being the contents of the exception message.

    .EXAMPLE
    'My log message' | Write-Log
    Appends a new Info line to the log with the message being the contents of the string.

    .EXAMPLE
    Write-Log 'My log message' -JSONFormat
    Appends a new Info line to the log with the message. The line will be in JSONFormat.